The remark, posted about an hour before the report on May hiring was released, did not indicate what the data would show, but Mr. Trump’s decision to draw attention to the report was noticed by the community of traders who obsess over that data. Traders in the bond and currency markets were particularly quick to react.

[Read more about the reactions to the message Mr. Trump posted on Twitter before the jobs report’s release last month.]

When the report was released at 8:30 a.m., it showed that the United States economy had added a better-than-expected 223,000 jobs in May and that the unemployment rate had dipped to its lowest level in 18 years.

Anyone who read the tea leaves via Mr. Trump’s Twitter feed might have been rewarded for placing the early trades. Bond yields, which rose after the 7:21 a.m. tweet, moved even higher after the report, for example.

The White House later confirmed that Mr. Trump had been briefed on the numbers the night before, as is typical.

To be clear: There is nothing unlawful with basing trades on Mr. Trump’s Twitter feed, and it is not clear if a 1985 rule that prohibits “employees of the executive branch” from commenting on the data until an hour after it is released applies to the president.

But it does mean that traders will get to wonder whether an early Twitter post will become a new element in the monthly jobs day ritual. On a holiday-shortened week in the United States, the anticipation of a presidential tweet has become an “interesting sidelight” that people have an eye on, said J.J. Kinahan, chief market strategist at TD Ameritrade.

“There was a movement in the market, there’s no question about that,” he said of the reaction last month, adding: “You have to see if it happens again before you say it’s something you have to pay attention to.”